This invention is directed to an improved process for the production of chloroprene (2-chlorobutadiene-1,3) by the dehydrochlorination of 3,4-dichlorobutene-1 and production of 2,3-dichlorobutadiene-1,3 by the dehydrochlorination of 2,3,4-trichlorobutene-1 or 1,2,3,4-tetrachlorobutane with aqueous sodium hydroxide.
According to most prior art processes, this dehydrochlorination is carried out with a solution of caustic soda at a temperature up to about 100.degree. C. or even higher. Chloroprene or 2,3-dichlorobutadiene-1,3, as the case may be, is removed from the crude reaction mixture by any convenient method, such as ordinary distillation, steam distillation, or phase decantation. The crude brine left behind can be disposed of, for example, by being pumped into wells from which it gradually seeps into the ground or by being injected into fresh or salt water streams. Because about 3 kg of brine are produced for each kg of chloroprene, and even larger amounts of brine are produced in the manufacture of 2,3-dichlorobutadiene-1,3, brine disposal is a serious problem, both from the standpoint of cost involved and environmental hazard created.